Over one quarter of children in the United States live with chronic health conditions. Many of these children require care from pediatric subspecialist physicians. However, 24% of children in need of subspecialty care have difficulty accessing this care due to geographic and socioeconomic barriers. Telemedicine is a novel approach for overcoming these barriers by delivering pediatric subspecialty across a distance using two-way audio-visual technology. Early data suggest that telemedicine has great potential to expand access and reduce disparities in pediatric subspecialty care. Yet much about telemedicine is poorly understood, with few studies examining how it is currently used or how to use it more effectively. Such data are important because uncritical expansion of telemedicine poses potential harms as well as potential benefits, including the potential for inappropriate use, unnecessary overuse, or exacerbated disparities if new technology is afforded to only a subset of the population. A critical need exists to identify current determinants of telemedicine use, barriers to use, and optimal strategies to ensure appropriate use by integrating subspecialty telemedicine into the patient- centered medical home. The overall goal of this study is to develop actionable strategies to advance the delivery of pediatric subspecialty care through telemedicine to overcome disparities and improve child health. In Aim 1, we will determine patient, subspecialist, primary care, and system-level factors associated with the use of telemedicine for ambulatory pediatric subspecialty care through analysis of a large, state-wide Medicaid database. In Aim 2, we will identify physician-perceived barriers to use of telemedicine for ambulatory pediatric subspecialty care through a national survey. In Aim 3, we will use data from prior aims along with clinician and parent input to develop a generalist-subspecialist e-consultation platform to improve appropriate use of telemedicine for ambulatory pediatric subspecialty care. Through these aims, we will significantly improve our understanding of the role of telemedicine in improving access to care for children with chronic conditions, setting the stage for future interventions to optimize outcomes through appropriate telemedicine use. With guidance from committed mentors and strong institutional support, the PI will also receive the necessary intensive mentorship, didactic education, and research experience to become an independent investigator, supporting career development objectives in advanced statistical modelling, implementation science, and clinical informatics. This work will provide essential preliminary data to support future grant applications to examine the impact of telemedicine use in observational data and to perform a pilot randomized controlled trial of the e-consultation platform developed herein. With these new skills and novel preliminary data, the PI will be poised to lead large studies to examine and improve the diffusion and impact of innovations in pediatric health care delivery, ultimately improving outcomes for children in need of subspecialty care and furthering NICHD?s mission of ensuring that all children achieve their full potential for healthy and productive lives.